In a dark room in her South Miami office, Dr. Nilza Kallos stared carefully at a glowing black, white and gray image of a patient’s breast.

Breast cancer has been her worst enemy since it killed her childhood friend in Brazil when they were in their 30s.

The disease remains the leading cause of death for women ages 40 to 55. And because one out of every eight women will be diagnosed with breast cancer, Kallos focuses on early detection, which can be difficult because many women have dense breast tissue.

Kallos is using a new breast imaging technique called a “Digital Tomosynthesis,” which takes several pictures to form a three-dimensional image of the breast, allowing her to spot minuscule tumors.

“The cancer can hide, because in a mammogram a cancerous mass is usually white, and the dense tissue is white, therefore cancer can look like Wite-Out on a white piece of paper,” Kallos said. “But if you put Wite-Out on a black paper, meaning the fatty tissue is black, then you see it very well."

Kallos’ new machine is called Hologic Selenia Dimensions 3D System, which the U.S. Food and Drug Administration approved in 2011. Since Kallos began using the $600,000 system last October, she has spotted tumors as small as 1 millimeter, or about the size of a pinhead.

She detected a 9-millimeter tumor in Judi Sebastian’s breast last year.

“It looks like a crab with little legs,” Kallos said. “In the two-dimensional mammogram, it doesn’t show. This would have been completely missed if it weren’t for the new machine.”

Sebastian, 65, said she had been getting mammograms since her 30s but a tumor had never been spotted until now. Her mother had survived breast cancer twice — first at 49 and then at 65 — and died of a stroke at 85.

The day of Sebastian’s mammogram was the eighth anniversary of her mother’s death. Kallos told her it was “the luckiest day” of her life.

Sebastian didn’t need chemotherapy or radiation. She also tested negative for the genetic mutation that increases the risk of breast cancer, known as BRCA. To be cautious, she decided to get a bilateral mastectomy, surgery to remove her breasts, in January.

“Even with my mother’s history, I didn’t think it would happen to me. I live a healthy lifestyle,” Sebastian said. “I have two daughters and a granddaughter, so I took all of the precautions that I could.”

During the mammogram, the woman stands in front of the machine. Her breast is pulled away from the body and held between two glass plates. The X-ray tube moves in a semi-circle around the breast to “take multiple pictures from many angles, while changing focus on different depths of tissue,” Kallos said.

The information is sent to a computer, which produces a clear image for Kallos to review.

“There is a 40 percent increase in the detection of invasive breast cancers and a 27 percent increase in the detection of all cancers,” said Kallos, referring to the results of a recent study. “It’s amazing.”

The two-dimensional mammogram costs $290 and the three-dimensional mammogram is done at no additional cost to the patient. Sebastian said it is the best money she has ever spent.

Under FDA regulations, a patient gets a 2-D mammogram before undergoing a 3-D one.

“Some patients may ask, ‘Why get the 2-D if you can get the 3-D?’ The FDA requires a 2-D mammogram,” said Kallos’ chief technologist, Rosie Petisco. “Getting both means more radiation, but the benefit outweighs the risk.”

Dr. Lori DeFillipo, a colleague of Kallos’, said she is concerned that the three-dimensional mammogram technique is not the standard screening protocol and thus is not covered by insurance.

“Insurance companies cover Viagra, but they don’t cover this test that can save women’s lives,’’ said DeFillipo. “That needs to change.”